cortical mechanisms of motor control Flashcards
somatic motor pathways
descending tracks deliver what from the brain the brain to the spinal cord
motor instructions
somatic motor pathways (descending)
are divided into what 2 groups
pyramidal tracts
indirect pathways (all others)
motor pathways contain how many neurons
at least 2
give examples of UMN
M1
pyramidal cell
give examples of UMN
M1
pyramidal cell
give examples of LMN
alpha motor neuron
basic functions of descending tracks
give 2 basic functions of the cortico-and rubrospinal descending track
- transmission of commands for skilled movements
- corrections of motor patterns generated by the spinal cord
basic functions of descending tracks
give 2 basic functions of the reticulospinal descending track
- activation of spinal motor programs for stepping and other stereotypic movement
- control of upright body posture
basic functions of descending tracks
give a basic function of the vestibulospinal descending tract
generation of tonic activity in antigravity muscles
layer V neurons from the primary motor coretx give rise to what
corticospinal tract
layer _ neurons from the primary motor cortex give rise to the corticospinal tract
V
layer V neurpns from the ____ _____ _____ give rise to the corticospinal tract
primary motor cortex
where does the pyramidal corticospinal pathway originate
in motor cortex
Layer _ pyramidal neurons are the UMNs
V
axons belonging to what form the corticospinal tract
Layer V
Layer V neurons axon’s form what
the corticospinal tract
UMN synapse where with LMNs
ventral horn
UMNs synapse in the ventral root with what
LMN’s
Where do LMNs (ventral horn motor neurons) exit
the spinal cord via the ventral anterior root
what do LMN activate
skeletal muscles
how do LMNs regulate fast and fine (skilled) movement
voluntarily
what regulates fast and fine movements
LMNs
the anterior/ventral corticospinal tract is responsible for the control of what
proximal musculature
what area of the brain controls proximal musculature
anterior ventral/corticospinal tract
the lateral corticospinal tract is responsible for the control of what
distal musculature
what area of the brain is responsible for the control of distal musculature
lateral corticospinal tract
Pyramids
most of the corticospinal axons decussate to enter what
descending lateral corticospinal tract
most _______ decussate to enter the descending lateral corticospinal tract
most of the corticospinal axons
UMNs do not pass through what
pyramids
what do extrapyramidal motor tracts regulate (3)
axial muscles that maintain balance and posture
muscles controlling coarse movements of the proximal portions of limbs
head, neck and eye movement
where does the rubrospinal tract originate
red nucleus of the mid brain
rubrospinal tract
voluntary/unvoluntary
choose one
voluntary
the rubrospinal tract is an alternative by which voluntary commands can be sent to ___
spinal cord
Rubrospinal tract
major/minor pathway in animals
major/minor pathway in humans
major in animals
minor in humans
activation of the rubrospinal tract causes excitation/inhibition of flexor muscles
excitation/inhibition of extensor muscles
excitation of flexor muscles
inhibition of extensor muscles
medial extrapyramidal pathway
the vestibulospinal tracts originate where
vestibular nuclei
Medial Extrapyramidal Pathways
the vestibulospinal tracts originate in the vestibular nuclei and are involved in what
posture, and in supporting the body against the force of gravity, mainly targeting extensors
medial extrapyramidal pathways
the tectospinal tracts originate where
superior colliculi
medial extrapyramidal pathways
the tectospinal tracts originate in the superior colliculi and mediate whar
orienting towards visual targets
the reticulospinal tract originates in the what
reticular formation
medial extrapyramidal pathway
what is the reticular formation
a diffuse collection of neurons in the pons and medulla
extrapyramidal pathways
what is the reticulospinal tract involved in
balance
what are the tracts in the medial extrapyramidal pathways
vestibulospinal
tectospinal
reticulospinal
how many cortical layers are there
7
electrical stimulation of motor cortical areas elicets what
movement of particular body parts
of the three motor areas, stimulation of what cortex requires the least amount of electrical current to elicit a movement
primary motor cortex
stimulation of what other 2 motor areas requires more electrical current to elicit movements
premotor cortex and supplementary motor area
the primary motor cortex is ___ organised
somatotopically
neuronal coding in the primary motor cortex
primary motor cortex neurons fire how long before the onset of a movement
5-100ms
primary motor cortex neurons can encode (4):
force of a movement
direction of a movement
extent of a movement
speed of a movement
What do M1 neurons encode
direction of a movement
force of a movement
what is the pre motor cortex involved in
motor planning
what is the supplementary motor area involved in
programming complex sequences of movement and coordinating bilateral movements
and selecting movements based on remembered sequences of movements
premotor neurons can signal __
an intention to move
pre motor cortex is sensitive to what
the behavioural context of a particular movement
premotor cortex neurons are sensitive to what
the intentions behind a movement, not just the movement itself
supplementary Motor area (SMA) responds to sequences of movement and to
mental rehearsal of movements
SMA
when movements are simple, such as making a repetitive movement of a single digit, what areas of the brain are activated (2)
contralateral primary motor cortex
primary somatosensory cortex
SMA
When a subject is asked to perform a complex sequence of finger movements, the SMA is activated in what way
what other brain regions are activated
bilaterally
and contralateral primary motor
somatosensory cortex
Reaching and Grasping
reaching and grasping require the transformation of visual information into what
a pattern of motor command
reaching and grasping require the transformation of visual information into a pattern of motor command, and involves connections between what 3 areas
visual, parietal, and premotor areas
reaching is mediated by what
a dorsal pathway running from the posterior occipital cortex to the mediodorsal parietal cortex , and on to the dorsal premotor cortex
mediated by dorsal pathway
posterior occipital cortex -> mediodorsal parietal cortex -> dorsal premotor cortex
grasping is mediated by what
a ventral pathway running from the dorsal extrastriate cortex to the AIP (anterior intraparietal area), and on to the ventral premotor cortex
